SAN FRANCISCO (CBS/AP) — The California Supreme Court on Monday tossed out the death sentence of a man convicted of murdering rock guitarist Dave Navarro’s mother and her friend nearly 30 years ago – a ruling that could affect the cases of Scott Peterson and other death row inmates.

The unanimous court said the trial judge presiding over the trial of John Riccardi improperly dismissed a prospective juror because of her conflicting written responses in a questionnaire asking her views of the death penalty.

The court said the judge was required to delve deeper into the juror’s death penalty views and determine if she could impose the death sentence is she believed prosecutors proved their case.

Peterson and a few other California death row inmates are appealing on similar grounds.

Peterson was convicted of killing his wife Laci, who was 8 months pregnant with their son, and dumping her body in San Francisco Bay on Christmas Eve 2002. Investigators believe Peterson either strangled or suffocated his wife.

Peterson has always maintained his innocence and claims in his appeal filed earlier this month that the trial judge presiding over his 2004 trial wrongly dismissed 13 jurors who said they opposed the death penalty but could follow the law and impose it if warranted.

In 1984, a narrowly divided U.S. Supreme Court ruled that reversal of the death penalty is automatic when potential jurors are dismissed because of their written answers to questions about their views on capital punishment.

Peterson’s attorney Cliff Gardner argued in his appeal that the mistake occurred in the Peterson trial and may be the basis of appeals of a few other death row inmates.

The last California execution occurred in 2006. Lawsuits in federal and state courts have forced a temporary halt to executions.

In its ruling Monday, the state high court upheld Riccardi’s murder conviction. Once a noted body builder, he was convicted of killing former girlfriend Connie Navarro in a jealous rage. Her friend Sue Jory also was killed. Navarro’s son played guitar for the band “Jane’s Addiction.”

It’s now up the California attorney general to determine if another penalty phase will be held or if Riccardi is taken off death row and sentenced to life in prison.

Chief Justice Tani Cantil-Sakauye said that ruling “compels the reversal of the penalty phase without any inquiry as to whether the error actually” led to an unfair trial. The chief justice wrote separately to urge the U.S. Supreme Court to reconsider the automatic reversal in such cases.

The juror in question, identified only by the initials “N.K.” in the ruling, wrote on the questionnaire that she supported California’s reinstatement of the death penalty and stated that it is not used enough.

But later in the questionnaire, the juror gave answers that suggest she opposes capital punishment.

“I’m afraid I could not feel right in imposing the death penalty on someone even though I feel it is nessasary (sic) under some circumstances,” N.K. wrote.

Cantil-Sakauye wrote that the trial court judge should have questioned her more instead of dismissing her as he did.

The chief justice said the juror’s conflicting answers meant either she “feared that actually being on a death jury would be difficult or uncomfortable, or she was advising the court that she could not impose a decision of death, even if the evidence warranted its application. From the questionnaire alone, we cannot possibly determine which scenario prompted her answers.”

Riccardi was arrested in Houston eight years after the killings when “America’s Most Wanted” aired a segment on the 1983 crime. A tipster recognized him and alerted authorities.

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